1. Technical Field
The technical field relates to a key structure and an electronic apparatus with the key structure.
2. Description of Related Art
An electronic apparatus that includes an apparatus case composed of an upper case and a lower case and a key input section disposed in the apparatus case has been known in the art as disclosed in JP 2008-159026A, in which the key input section includes a key sheet that is disposed on the inner face of the upper case and that includes key button portions exposed on the upper face of the upper case, the key sheet has a number of pin holes excluding the areas corresponding to the key button portions, the upper case includes a number of fitting protrusions in the inner face that are inserted to fit in the respective number of pin holes of the key sheet.
A key sheet is typically made of elastic rubber, in which skirts are provided between contacting portions and a sheet base portion to keep the contacting portions constituting the key button portions apart from the sheet base portion of the key sheet, and a conductive membrane of carbon or the like is formed on the back face of the contacting portions.
The key button portions may be constituted by the contacting portions themselves on which signs (e.g. alphabets, etc.) of the key button portions are directly printed or by the contacting portions and resin keys attached thereon.
In an electronic apparatus using such a key sheet, a control circuit board of the electronic apparatus is disposed on the back side of the key sheet such that electrodes for detecting a user key operation are arranged corresponding to the key button portions.
When a user pushes down the front side of a key button portion, the skirt is buckled so that the key button portion comes in contact with an electrode of the control circuit board, and the electrode of the control circuit board thereby turns to be conductive. The electronic apparatus thus detects the user key operation.
Increasing the size of the key button portions improves the visibility of the key button portions. However, when the user pushed down a key button portion so that a skirt is buckled, the skirt is less likely to be uniformly folded, which may cause an unintended double click.